Well the constant idea that all transwomen are secretly men trying to get into women's spaces to sexually assault them, that is trotted out a lot on the feminist board.
I have rarely seen an argument that says 'all transwomen' are secretly men trying to get into women's spaces. That must be you drawing that conclusion from the discussions about how transwomen are male and still retain a similar male pattern behaviour towards violence and sexual assault. I see a lot of discussion about the fact that also there are predatory males who may mis-use the trust that a transwoman should be welcomed in a female space (including hospital wards and prisoners) because people have misused trust in the past eg. abusive priests, scout leaders etc. That is the discussions I have seen. But I don't read every single thread there.
Another is that every transgendered person has mental health issues and needs urgent treatment instead of being able to identify as they like, this is also mentioned frequently on there.
Again, you seem to be generalising considerably. We are told that the basis for most people wishing to take the step to transition is gender dysphoria and from statistics around young people transitioning at the moment, there seems to be overwhelmingly co-morbidities that are being untreated. Are you saying that gender dysphoria is NOT a mental health issue?
Even ex gender clinic psychiatrists have expressed concern that people are going into the clinics believing that transitioning is the cure all and that might explain why post-transition suicide ideation is so high.
Another is referring to them as "beared blokes in dresses" (this one I've always managed to report and get removed). Yes. This would be transphobic and you should report this (unless it was actually someone who identified as a bloke and liked dresses).
I am not going to discuss the racist element as to be honest, I have not really read that widely on those threads. But any racist elements should definitely be deleted.